Not Applicable
The present invention relates to a self-cleaning sanitary device for animals. The invention also relates to indoor and outdoor self-cleaning sanitary devices.
Many forms of sanitary devices have been developed to collect bodily waste from animals. The most common of these are litter boxes used by household pets, such as cats and dogs. Although litter boxes are generally accepted by animals, regular daily disposal of the solid waste is recommended. Lack of regular cleaning can produce odors and force the animals to navigate around, or unintentionally dig up, waste from previous days. This can encourage the animals to find less-disagreeable places to relieve themselves and weaken their xe2x80x9ctoilet trainingxe2x80x9d. Similarly, releasing animals outdoors to relieve themselves can result in poor xe2x80x9ctoilet habitsxe2x80x9d that can become a source of aggravation and conflict with other users of the area, such as neighbors and passers-by. Clearly, a self-cleaning litter device is desirable to eliminate the disagreeable and often avoided task of manually cleaning litter.
The recent introduction and widespread availability of clumping litter has influenced the design of many self-cleaning litter devices. Clumping litter reacts with liquid waste (urine) to form solid clumps. The solid clumps can be collected in the same way as other solid waste (feces) to provide a cleaner litter area. Sufficient litter depth, however, is required to prevent the clumping litter from solidifying against, and bonding to, the bottom of the litter box.
Many self-cleaning litter devices are motorized and automated to operate unattended for extended periods. Solid waste is extracted from the litter and stored in a waste receptacle. A means is generally provided to reduce or prevent excessive odors from escaping the waste receptacle. The automated versions have short cleaning cycles (generally less than a few minutes) that are activated after a suitable time delay to allow the clumping litter to react. Short cleaning cycles however can produce fast, unexpected movements and motor noise that can easily scare the animals or increase their discomfort during use. The automated versions therefore use sensors and start/stop controls to detect if animals have used the devices and to avoid operating the cleaning cycles while animals are in the devices. Sensors and controls however increase the complexity and cost of the devices. A few of the more relevant self-cleaning litter designs are briefly described below.
Motorized self-cleaning litter devices using rectangular chambers (similar to the common litter box) are disclosed in, for example, U.S. Pat. No. 5,226,388, U.S. Pat. No. 5,477,812 and U.S. Pat. No. 5,544,620. Rake motion includes a forward stroke to extract solid waste from the litter; an upward stroke to lift the waste over the enclosing wall and dump it in a waste receptacle; and a backward stroke to smooth the litter and return the rake to its xe2x80x9cparkedxe2x80x9d position. A disadvantage with these devices is litter buildup at the ends of the chamber due to the forward and backward strokes of the rake. This can interfere with proper rake operation and lead to reduced litter depth near the center of the chamber. Burying habits of the animals can further upset the litter distribution and can make extended periods of unattended operation problematic. In addition, waste deposited on the wrong side of the rake (e.g., during an interrupted cleaning cycle) is pushed to the rake""s xe2x80x9cparkedxe2x80x9d position during the backward stroke and must be manually removed.
Cylindrical self-cleaning litter devices using horizontally-positioned drums have been disclosed in, for example, U.S. Pat. No. 4,120,264, U.S. Pat. No. 5,048,464 and U.S. Pat. No. 5,509,379. Generally, these devices include a rake attached to the inner surface of the drum which sifts the litter during drum rotation. The cylindrical wall of the drum supports the litter and rises out of both sides of the litter area at an angle. Litter depth varies from a maximum near the center of the litter area to zero depth along the sides. Minimal litter depth along these sides can easily result in exposure of the cylindrical wall surface to liquid waste. This can cause clumping litter to adhere to the cylindrical wall surface and must be cleaned manually.
A self-cleaning litter device is described in U.S. Pat. No. 4,574,735 comprising a bowl-shaped, circular litter chamber. The device uses a stiff first rake, with horizontal tines extending in a curved or spiral shape from a spindle along the central axis of the chamber, to urge solid waste to the outer perimeter of the chamber during rake rotation. A flexible second rake then pushes the solid waste up a bordered ramp along the outer perimeter of the chamber into an opening that leads to a waste receptacle. Both rakes are driven by the spindle and quickly circle the chamber in 6 to 30 seconds. A disadvantage with this design however, is that the curvature of the stiff rake can also push solid waste against the border of the ramp. Solid waste can become trapped and smeared into the rake and along the border of the ramp which must be cleaned manually; or can break apart producing smaller pieces that may not be collected by the rakes. The side wall of the chamber can also become smeared with solid waste during contact to deflect the solid waste into a circular path. The means to remove solid waste from the chamber relies on contact with the floor of the ramp to deflect the flexible rake out of the litter. Over time, severe wear of the rake and the ramp can result due to the abrasive nature of most litters. In addition, the centrally-based drive system, while capable of meeting the demands of the rakes and accommodating the described means to remove solid waste from the chamber, inherently requires strong components and a strong support structure to transmit the forces needed at the outer ends of the cantilever-based rakes.
U.S. Pat. No. 5,931,119 discloses a self-cleaning litter device wherein a circular pan rotates past a rake during the cleaning cycle. The rake is normally vertical, outside the pan, and cantilevers into the pan to sift the litter. After sifting, the rake is rotated (to scoop the sifted waste) and cantilevered out of the litter pan. The solid waste eventually rolls down the rake (as it is cantilevered up) to fall into a waste receptacle. Drive mechanisms are required for both the pan and the rake. The means to cantilever and rotate the rake requires strong, accurate components and a strong support structure to sustain the forces produced during the sifting action and prevent the rake tines from scraping the bottom of the circular pan. In addition, the open waste receptacle cannot prevent the solid waste, now exposed to the air, from releasing odors back into the pan area and escaping the device. This requires frequent emptying of the waste receptacle and significantly reduces the period of unattended operation.
Many automated self-cleaning sanitary devices have unique and complicated approaches to reducing or preventing the escape of odors from the waste receptacle. U.S. Pat. No. 4,574,735 describes a rotating waste receptacle that mixes the waste with sanitizing and deodorizing chemicals. U.S. Pat. No. 5,477,812, U.S. Pat. No. 5,544,620, and U.S. Pat. No. 5,107,797 describe devices that combine a means to open and close a lid on the waste receptacle with the means to move the rake through the litter. U.S. Pat. No. 5,048,464 describes a rocking lid on a waste receptacle that tilts open by the weight of the solid waste. Because solid waste can be light in weight, the rocking lid design must be well balanced. In addition, the rocking lid design requires a gap around the perimeter of the lid to prevent jamming. The gap, however, can also allow odors to escape. Further, the rocking lid opens inward, into the waste receptacle, which reduces its maximum capacity.
Although a wide variety of designs exist for self-cleaning sanitary devices in general and self-cleaning litter devices in particular, many have drawbacks which limit their benefits or significantly increase their cost. A need exists for a simple self-cleaning litter device that reduces manual involvement in the disagreeable tasks of maintaining a clean litter area. There is also a long felt need for an automatically self-cleaning litter device that can operate unattended for extended periods to provide a clean litter area for animals and is available at reasonable cost. There is also a need for similar devices used outdoors.
The present invention sets out to obviate the problems identified within the prior art self-cleaning sanitary devices and to meet the needs described above.
The present invention relates to a self-cleaning sanitary device for animals. The invention also relates to indoor and outdoor self-cleaning sanitary devices.
According to the present invention there is provided a self-cleaning liner device that extracts solid waste from a litter material contained therein during use, comprising,
a substantially circular chamber bounded by a side wall;
a rake;
a means to produce a rotational motion between the rake and the chamber;
a means to prevent the rake from pushing the solid waste against the side wall of the chamber; and
a means to remove the solid waste collected by the rake from the chamber.
Preferably, the rake extends from a central axis of the chamber to an outer end near to the side wall of the chamber, and comprises a plurality of tines. The tines may extend with generally downward slopes into the chamber to deflect solid waste upwards. Furthermore, one or more tines may be helically-shaped with each tine curved with a radius of curvature about equal to its radial distance from the central axis of the chamber. This invention also pertains to the self-cleaning litter device as defined above with the rake also comprised of at least one deflector.
This invention also considers the self-cleaning litter device as defined above wherein the means to produce the rotational motion between the rake and the chamber comprises a drive means in operative association with a substantially circular sleeve adjacent the side wall of the chamber causing the sleeve to rotate; the sleeve being attached to the outer end of the rake causing the rake to rotate. Alternatively, the means to produce the rotational motion between the rake and the chamber comprises a drive means in operative association with the chamber causing the chamber to rotate. The invention also considers the self-cleaning litter device as defined above wherein the means to produce a rotational motion between the rake and the chamber may be applied near the side wall of the chamber. The invention also pertains to the self-cleaning litter device as defined above wherein the drive means may be selected from a group consisting of a motor, a wind turbine and a hand crank.
This invention also includes the self-cleaning litter device as defined above, wherein the means to prevent the rake from pushing solid waste against the side wall of the chamber comprises at least one tine nearest the outer end of the rake positioned in advance of adjacent inner tines so that contact between the solid waste and the tines nearest the outer end of the rake does not direct solid waste outwards. This invention also pertains to the self-cleaning litter device as defined above also comprising a platform attached to the outer end of the rake.
This invention is also directed to the self-cleaning litter device as defined above wherein the means to remove the solid waste from the chamber, collected by the rotating rake and sleeve, comprises;
a tunnel in the side wall of the chamber; and
the sleeve having an opening, immediately adjacent the rake, so that when the opening in the sleeve aligns with the tunnel, the solid waste is removed from the chamber.
This invention also pertains to the self-cleaning litter device as defined above also comprising a scoop positioned in the tunnel and forced into the chamber by a biasing means, when the opening in the sleeve aligns with the tunnel, to deflect the solid waste into the tunnel before being forced back into the tunnel.
This invention also pertains to the self-cleaning litter device as defined above, wherein the rotational motion between the rake and the chamber may occur at a speed less than 10 cm per minute. Preferably, the rake to chamber rotational motion is continuous, however, the self-cleaning litter device may be operated intermittently and may be comprised of a timer or sensors/controls to detect an animal and control the means to produce the rotational motion.
The invention also pertains to the self-cleaning litter device as defined above further comprising a means to drain liquid waste from the chamber.
According to a further aspect of the present invention there is provided a waste receptacle for use with a self-cleaning sanitary device to collect solid waste comprising,
a container;
a cover that fits over the container and further comprises;
a tilted frame around an opening; and
a trapdoor covering the opening that is sufficiently light in weight to be pushed open by the solid waste and closed by gravity to rest on the tilted frame.
Preferably the trapdoor can flex under its own weight to conform to the surface of the tilted frame to reduce odors. The invention also pertains to the waste receptacle as defined above also comprising a ramp in front of the trapdoor to assist the solid waste in pushing the trapdoor open.
According to a further aspect of the present invention there is provided a rake to extract solid waste from a substantially circular chamber of a self-cleaning litter device comprising a plurality of tines that extend with generally downward slopes into the chamber to deflect or push solid waste upwards and wherein one or more tines may be helically-shaped with each tine curved with a radius of curvature about equal to its radial distance to the central axis of the circular chamber. This invention also pertains to the rake as defined above also comprised of at least one deflector.
Advantages associated with the self-cleaning litter device of the present invention include the capacity to prevent the rake from pushing solid waste against the side wall of the chamber before being removed from the chamber. A further advantage is the capacity to produce sifting of the litter contained in the chamber by rotating the rake or the chamber. A further advantage is the capacity to produce a rotational motion between the rake and the chamber by pushing the outer end of the rake or the side wall of the chamber while simultaneously providing a means to remove solid waste collected by the rake from the chamber. A still further advantageous aspect of the invention is the capacity to use helically-shaped tines on the rake to reduce the amount of litter disturbed during sifting and the force required to sift the litter. Another advantageous aspect of the invention is the capacity to use deflectors on the rake to redistribute litter within the chamber. Another advantageous aspect of the invention is the capacity to use a slow rotational motion between the rake and the chamber that permits continuous sifting of the litter even while an animal is in the device and eliminates the need for control circuitry, however, such circuitry may be employed if desired. Another advantageous aspect of the invention is the capacity to use a wind-powered drive means to produce an outdoor self-cleaning litter device that is independent of electrical power. A further advantageous aspect of the invention is the capacity to provide a means for draining liquid waste from the chamber to operate with nonabsorbent litter. A further advantageous aspect of the invention is an odor-suppressing waste receptacle with a trapdoor that operates independently of the means to extract waste from the litter.
This summary of the invention may not describe all the embodiments or features of the invention and in no way implies and should in no way be construed that the invention is limited to the described embodiments and combinations of features but that other embodiments, variations, features, combinations or sub-combinations of features may also apply.